Troubleshooting: Blossom End Rot

A common plague of tomatoes, peppers, and eggplants is the brown spot that appears at the bottom, or blossom end, of the fruit. There is no cure but to pluck it immediately and take measures to avoid losing anymore fruit.

This blossom end rot is caused by a calcium deficiency so that the end of the fruit furthest from the plant does not absorb enough calcium to see it through to development. Several gardening companies will tell you you need to buy expensive bags of lime (which are varying calcium compositions) dependent on your soil Ph, but in general the home grower can avoid this through the use of egg shells and mulch.

If there is, in fact, a calcium deficiency in the soil the simple application of crushed eggshells buried at the base of the plant, preferably while the plant is young, will provide sufficient calcium throughout the growing season. However, calcium deficiencies are actually rare in heavily composted soil, which many of you are using if growing in containers and small areas. The more likely issue is inconsistent moisture that enables the plant to absorb the calcium.

This is where mulch comes in. Drastic fluctuations in the soil moisture prevent the plant from absorbing calcium leading to inconsistent fruit production. The solution is to apply an even layer of mulch over the exposed soil in the garden, leaving about 4 inches around plant stems. Because the mulch will break down over time, do not apply additional nitrogen-rich fertilizers as these too can interfere with the absorption of calcium.

Other common issues related to moisture levels are splitting and the development of small white spikes along the stems, which are tiny roots trying to develop. Splitting occurs when water levels have been low and then increase quickly. The skin splits open as the tomato swells with the water. The tiny roots along the stem occur when the plant stays too wet. To avoid both of these, mulching and a regular watering regimen should be practiced. Water slowly either with drip irrigation or a soaker hose nozzle applying water to the base of the plant, not stems and leaves. To avoid over watering only water when the soil no longer feels evenly damp when you poke a finger about 2 inches below the surface of the soil. If you anticipate a heavy rain and have tomatoes that are almost ripe, go ahead and pick them if you want to avoid the natural splitting that might follow.

Intrepid Gardens began in February 2013 as an experimental garden in Colombo, Sri Lanka seeking to provide families and community partners with the resources to grow sustainable food systems in tropical and urban landscapes. With our own 60 square foot rooftop slab, we began experimenting with growing solutions any urbanite could use. Here we share applications and news in permaculture, organics, and sustainable urban living.